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1.
Gut ; 46(3): 415-9, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10673307

RESUMO

BACKGROUND: Wilson's disease is a rare but treatable condition that often presents diagnostic dilemmas. These dilemmas have for the most part not been resolved by the identification and cloning of the Wilson's disease gene. AIMS: To report our experience over three decades with patients with Wilson's disease in order to illustrate the diverse patterns of presentation and thereby broaden the approach to diagnosis. METHODS: Clinical and laboratory findings of 30 patients with Wilson's disease were reviewed. RESULTS: Twenty two patients presented with liver manifestations (eight with fulminant hepatic failure and 14 with chronic liver disease), three with neurological disease, and one with haemolysis; four were asymptomatic siblings of patients with Wilson's disease. Seventy per cent were diagnosed within six months of the onset of symptoms, but diagnosis was delayed for up to nine years. Age range at diagnosis was wide (7-58 years) and five patients were over 40. In patients presenting with non-fulminant disease, 18% had neither Kayser-Fleischer rings nor low caeruloplasmin concentrations. Increased liver copper concentrations were found in all but one patient who had undergone six years of penicillamine treatment. In fulminant hepatic failure (n=8) additional features helpful in the diagnosis included evidence of haemolysis, increased urinary copper (range 844-9375 microg/24 h), and a high non-caeruloplasmin copper (range 325-1743 microg/l). CONCLUSIONS: The diagnosis of Wilson's disease still depends primarily on the evaluation of clinical and laboratory evidence of abnormal copper metabolism. No one feature is reliable, but the diagnosis can usually be made provided that it is suspected. Wilson's disease should be considered in patients of any age with obscure hepatic or neurological abnormalities.


Assuntos
Degeneração Hepatolenticular/diagnóstico , Adolescente , Adulto , Criança , Cobre/metabolismo , Feminino , Degeneração Hepatolenticular/metabolismo , Degeneração Hepatolenticular/terapia , Humanos , Testes de Função Hepática , Transplante de Fígado , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento
2.
Nutrition ; 15(9): 661-4, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10467609

RESUMO

The longevity of recipients of liver transplant may be compromised by spinal osteoporosis and vertebral fractures. However, femoral neck fractures are associated with a higher morbidity and mortality than spine fractures. As there is little information on bone loss at this clinically important site of fracture, the aim of this study was to determine whether accelerated bone loss occurs at the proximal femur following transplantation. Bone mineral density and body composition were measured at the femoral neck, lumbar spine and total body, using dual x-ray absorptiometry in 22 men and 19 women, age 46 +/- 1.4 y (mean +/- SEM) before and at a mean of 19 mo after surgery (range 3-44). Results were expressed in absolute terms (g/cm2) and as a z score. Before transplantation, z scores for bone mineral density were reduced at the femoral neck (-0.47 +/- 0.21 SD), trochanter (-0.56 +/- 0.19 SD), Ward's triangle (-0.35 +/- 0.14 SD), lumbar spine (-0.76 +/- 0.13 SD), and total body (-0.78 +/- 0.15 SD) (all P < 0.01 to < 0.001). Following transplantation, bone mineral density decreased by 8.0 +/- 1.7% at the femoral neck (P < or = 0.01) and by 2.0 +/- 1.2% at the lumbar spine (P < or = 0.05). Total weight increased by 12.2 +/- 2.3%, lean mass decreased by 5.7 +/- 1.4%, while fat mass increased from 24.1 +/- 2.0% to 35.1 +/- 1.8% (all P < or = 0.001). Patients with end-stage liver disease have reduced bone mineral density. Liver transplantation is associated with a rapid decrease in bone mineral density at the proximal femur, further increasing fracture risk and a reduction in lean (muscle) mass, which may also predispose to falls. Prophylactic therapy to prevent further bone loss should be considered in patients after liver transplantation.


Assuntos
Composição Corporal , Fêmur , Transplante de Fígado/efeitos adversos , Osteoporose/etiologia , Absorciometria de Fóton , Tecido Adiposo , Adulto , Idoso , Índice de Massa Corporal , Peso Corporal , Densidade Óssea , Feminino , Humanos , Estudos Longitudinais , Vértebras Lombares , Masculino , Pessoa de Meia-Idade
3.
Clin Exp Pharmacol Physiol ; 25(2): 110-3, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9493498

RESUMO

1. A 50 microL bolus dose containing (+/-)-propranolol hydrochloride (200 microg) and [14C]-sucrose, or antipyrine (2 mg) and [14C]-sucrose, or [14C]-taurocholate sodium was injected into the portal vein of the isolated perfused rat liver preparation and perfusate outflow samples were collected frequently for the next 30 min. After a 20 min washout period this procedure was repeated. 2. [14C]-Sucrose, antipyrine and [14C]-taurocholate each eluted as a single peak at 18, 31 and 28 s, respectively, after each dose. In contrast, propranolol eluted with two peaks at approximately 18 and 128 s after dosing. 3. There was no significant difference in dose-corrected area under the outflow curve (AUC) for [14C]-sucrose, antipyrine or [14C]-taurocholate between the first and second doses whereas the mean propranolol AUC for the second dose was only 0.577+/-0.439 that for the first dose (P<0.05). 4. Unmetabolized propranolol accounted for more than 80% of the drug in hepatic tissue for the first and second doses at 18 s and greater than 50% at 128 s, and there was no significant difference in these values at each time between the first and second doses. 5. These findings suggest that for an avidly extracted drug, such as propranolol, systemic availability of orally administered drug will be highly dependent on factors that influence the hepatic tissue binding of the drug.


Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/farmacocinética , Fígado/metabolismo , Propranolol/farmacologia , Propranolol/farmacocinética , Animais , Área Sob a Curva , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Técnicas In Vitro , Fígado/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley
4.
Gut ; 36(6): 927-30, 1995 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-7615286

RESUMO

A prevalence study of primary biliary cirrhosis was carried out in the state of Victoria, Australia, by means of a mail survey of specialist physicians and a review of hospital records. Eighty four cases were identified, giving a prevalence of 19.1 per million population (95% confidence limits (CI) 15.3, 23.7), which is among the lowest in published reports. The prevalence in the Australian born, at risk population (women over the age of 24) was 51 per million (95% CI 37.5, 67.9). Both these figures are considerably lower than those in populations of similar age distribution in the UK and northern Europe. Since most Victorians are descended from British or European settlers, the low prevalence of primary biliary cirrhosis in this study supports the hypothesis that local environmental factors may be important in the pathogenesis of this disease.


Assuntos
Cirrose Hepática Biliar/epidemiologia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Emigração e Imigração , Feminino , Humanos , Cirrose Hepática Biliar/etnologia , Cirrose Hepática Biliar/etiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Vitória/epidemiologia
5.
Biochem Pharmacol ; 48(4): 846-9, 1994 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-8080458

RESUMO

The contribution of intracellular storage to hepatic uptake of the high clearance drug, omeprazole, was examined in the recirculating isolated perfused rat liver preparation. Following injection of [3H]omeprazole (7.5 microCi, 5 mg) into the portal vein over 1 min, livers were perfused for 5 min (N = 3) or 30 min (N = 3) and then homogenized at 4 degrees and fractionated by differential centrifugation. Radiolabelled omeprazole and metabolites were determined by scintillation counting of fractions of eluant from HPLC. Seventy per cent of drug had been taken up by the liver at 5 min and 85% at 30 min, with unchanged drug representing 43 and 7.4%, respectively, of drug taken up. At both times, 70-75% of intracellular unchanged drug and the major metabolites were located in the cytosol, and the cytosol:perfusate concentration ratio was approximately 10:1. Mitochondrial, lysosomal and microsomal fractions contained relatively little drug. Extensive cytosolic binding of omeprazole therefore contributes substantially to the initial avid hepatic first-pass uptake of this drug.


Assuntos
Fígado/metabolismo , Omeprazol/farmacocinética , Animais , Citosol/metabolismo , Masculino , Omeprazol/administração & dosagem , Omeprazol/metabolismo , Veia Porta , Ratos , Ratos Sprague-Dawley , Frações Subcelulares/metabolismo
6.
Aust N Z J Med ; 24(2): 141-8, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8042941

RESUMO

BACKGROUND: The clinical role of the transjugular intrahepatic portal-systemic shunt (TIPS) has not been fully defined. AIMS: To determine the technical results of TIPS and the clinical outcome of patients undergoing the procedure. METHODS: Retrospective audit of the results of the first 31 procedures performed in Melbourne. RESULTS: Thirty procedures were performed for variceal haemorrhage, one procedure was for ascites. The aetiology of the liver disease was cirrhosis due to alcohol in 20, cryptogenic in five, chronic viral infection in four, and autoimmune chronic active hepatitis in one. Nodular regenerative hyperplasia was present in one patient. Seventy-seven per cent of procedures were considered successful based on the angiographic demonstration of shunt patency at the end of the procedure. The in-hospital mortality in all patients undergoing TIPS was 45% and was 42% in patients undergoing technically successful TIPS. Only age could be identified as predictive of death in hospital. In patients leaving hospital, we found a rebleeding rate of 57% with one patient dying of bleeding, one requiring balloon tamponade and two requiring variceal sclerotherapy. Hepatic trauma was documented in six cases, shunt thrombosis in four cases, stent displacement in two cases and severe hepatic encephalopathy in one case. CONCLUSIONS: TIPS has the potential to decompress the portal venous system, but the procedure is technically complex and should be performed in the knowledge that mortality and morbidity can be relatively high, particularly in patients whose condition is poor.


Assuntos
Varizes Esofágicas e Gástricas/cirurgia , Hemorragia Gastrointestinal/cirurgia , Derivação Portossistêmica Cirúrgica/efeitos adversos , Adulto , Idoso , Varizes Esofágicas e Gástricas/complicações , Feminino , Humanos , Hiperplasia , Fígado/patologia , Cirrose Hepática/complicações , Masculino , Auditoria Médica , Pessoa de Meia-Idade , Derivação Portossistêmica Cirúrgica/mortalidade , Complicações Pós-Operatórias , Estudos Retrospectivos , Stents , Resultado do Tratamento
7.
Mech Ageing Dev ; 73(3): 157-68, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8057687

RESUMO

Uptake from the circulation and subsequent intracellular degradation of foreign and potentially harmful substances are key functions of hepatic Kupffer cells. While ageing is generally associated with decreased clearance by the reticulo-endothelial system, the effect of ageing on specific Kupffer cell functions is poorly understood. This study measured the ability of Kupffer cells of isolated perfused rat livers from young and old rats to both phagocytose and subsequently degrade exogenous radiolabelled mitochondria. Using electron microscopy and stereological techniques it was determined that there was no change in the volume density of Kupffer cells between 2 and 24 months, implying that the size of the Kupffer cell population increased (along with the total liver size) with age. However, despite this increase size there was no parallel increase in the capacity of the liver to take up or degrade radiolabelled mitochondria, implying that, in aged rats, Kupffer cell uptake and intracellular degradation was less efficient.


Assuntos
Envelhecimento/metabolismo , Células de Kupffer/fisiologia , Mitocôndrias Hepáticas/metabolismo , Animais , Radioisótopos de Carbono , Feminino , Técnicas In Vitro , Inativação Metabólica , Células de Kupffer/metabolismo , Perfusão , Ratos , Ratos Sprague-Dawley
8.
Clin Exp Pharmacol Physiol ; 19(7): 537-9, 1992 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1499150

RESUMO

1. The hepatic reticulo-endothelial cell population is generally assumed to increase in size, along with the liver, during ageing in rats. However, this has not been rigorously established. 2. Using electron microscopy and stereological techniques, the present study has shown that the volume densities of hepatocytes and Kupffer cells (and probably also of endothelial cells, fat storing cells and the extracellular space) of the livers of female Sprague-Dawley rats are the same at 2 and 24-25 months of age. 3. This result indicates that the increase in size of the liver during ageing in the rat is associated with an equivalent increase in the volume of each cell population and the extracellular space.


Assuntos
Envelhecimento/fisiologia , Espaço Extracelular/fisiologia , Células de Kupffer/citologia , Fígado/citologia , Animais , Feminino , Ratos , Ratos Endogâmicos
10.
J Chromatogr ; 574(2): 205-11, 1992 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-1618951

RESUMO

A high-performance liquid chromatographic method was developed for resolving heterogeneous preparations of fluorescently labelled endotoxin derived from Escherichia coli (Serotype 0111:B4) into separate lipopolysaccharide sub-groups. The endotoxin was chromatographed on an analytical gel permeation column using a mobile phase of acetonitrile (20%, v/v) and 100 mM phosphate buffer (pH 7.75). Four fluorescent peaks were resolved, representing sub-groups of markedly different molecular sizes. Three of the four sub-groups contained the core polysaccharide 2-keto-3-deoxyoctonate, confirming that they contained lipopolysaccharide. Fluorescein isothiocyanate (FITC)-labelled endotoxins derived from Vibrio cholerae and Salmonella minnesota chromatographed using the same system eluted with distinctly different patterns of peaks from each other and from E. coli. Extraction of E. coli FITC-endotoxin from a buffer solution using a phenol-diethyl ether method and subsequent chromatography allowed the determination of three of the four fluorescent sub-groups over the concentration range 1-15 micrograms/ml.


Assuntos
Endotoxinas/metabolismo , Lipopolissacarídeos/isolamento & purificação , Fígado/metabolismo , Animais , Toxinas Bacterianas/isolamento & purificação , Toxinas Bacterianas/metabolismo , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Técnicas In Vitro , Lipopolissacarídeos/metabolismo , Ratos , Salmonella/metabolismo , Espectrometria de Fluorescência , Vibrio cholerae/metabolismo
11.
Med J Aust ; 154(10): 698-701, 1991 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-2034154

RESUMO

OBJECTIVE: To alert clinicians to the hepatotoxic potential of Augmentin (amoxycillin and clavulanic acid), a widely prescribed antibiotic, in susceptible patients, and to point out that the hepatic illness may be delayed but serious and protracted. DESIGN AND SETTING: Case reports of patients with Augmentin-induced jaundice referred to the gastroenterology departments in three major teaching hospitals, and a review of cases reported to the Australian Adverse Drug Reactions Advisory Committee (ADRAC). PATIENTS: Eight patients with nine episodes of Augmentin-induced jaundice personally treated by the authors from March 1988 to February 1990 are described. A further 19 patients reported to ADRAC from May 1987 to November 1989 are discussed. All patient histories were carefully reviewed to ensure that there was a temporal relationship between the course of Augmentin and the onset of the hepatitic illness and that other causes of jaundice were reasonably excluded. RESULTS: Jaundice developed in some of these patients several weeks after drug treatment was completed. The illness may be protracted over many weeks. As yet, there has been no case of progressive disease leading to the liver failure. CONCLUSIONS: The data suggest that a hypersensitivity reaction to clavulanic acid is the likely cause of the jaundice. Therefore, Augmentin, although an important antibiotic, should be reserved for severe infections for which amoxycillin is unsuitable.


Assuntos
Amoxicilina/efeitos adversos , Ácidos Clavulânicos/efeitos adversos , Icterícia/induzido quimicamente , Adulto , Idoso , Combinação Amoxicilina e Clavulanato de Potássio , Hipersensibilidade a Drogas/etiologia , Quimioterapia Combinada/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
12.
Clin Pharmacol Ther ; 47(4): 463-9, 1990 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-2328554

RESUMO

The present study was designed to compare the pharmacokinetic handling of a single oral dose of nicardipine in normal subjects and in patients with hepatic cirrhosis and to compare the sensitivity of the two groups to its hypotensive effect. Nicardipine plasma concentrations were substantially higher in the subjects with hepatic cirrhosis with impaired antipyrine clearance, as shown by a significantly higher average Cmax and AUC. The terminal elimination half-life in this group varied from 0.8 to 60.2 hours (median, 11.7 hours), compared with 0.6 to 4.1 hours (median, 1.4 hours) in the group of eight subjects with normal liver function. In the cirrhotic patients with impaired antipyrine clearance, the AUC of the pyridine metabolite averaged 10% of that of the parent drug, whereas in normal subjects the ratio averaged 48%. This finding suggests less conversion of nicardipine to this metabolite in subjects with impaired hepatic function. Peak blood pressure decreases were greater in the cirrhotic group, which was in keeping with the higher plasma levels in these subjects.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Cirrose Hepática/fisiopatologia , Nicardipino/farmacocinética , Adulto , Idoso , Antipirina/farmacocinética , Biotransformação , Feminino , Meia-Vida , Humanos , Fígado/metabolismo , Fígado/fisiopatologia , Cirrose Hepática/sangue , Cirrose Hepática/metabolismo , Masculino , Pessoa de Meia-Idade , Nicardipino/sangue , Nicardipino/farmacologia , Distribuição Aleatória
13.
Clin Exp Pharmacol Physiol ; 16(1): 25-32, 1989 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2706806

RESUMO

1. Perhexilene, a long-acting anti-anginal drug, can induce adverse effects on the liver which may be dose-dependent. At high concentrations, perhexilene causes marked morphological changes in hepatocyte lysosomes. The current study examined the effect of 'therapeutic' doses of perhexilene on hepatic lysosomal function, particularly the biliary release of lysosomal enzymes, using an isolated perfused rat liver (IPRL) model. 2. Pharmacokinetic studies demonstrated that clearance of single doses of perhexilene by the perfused rat liver was dose-dependent and established a 'therapeutic' dose of 0.6 mg using the IPRL. A 5 day pretreatment regimen of 20 mg/kg per day was shown to produce 'therapeutic' perhexilene concentrations of 150-210 ng/ml. 3. At perhexilene concentrations equating the 'therapeutic' range in man, the major effect of perhexilene was at the biliary pole of the hepatocyte. In 5 day pretreatment dose studies, lysosomal enzyme excretion into bile was markedly increased. In single dose studies, the increase in biliary lysosomal enzyme output partially reflected an increase in bile water production which was not seen with the 5 day pretreatment regimen. Hepatic and perfusate lysosomal enzyme activities were not affected. 4. This selective effect of perhexilene on hepatocyte-to-bile lysosomal excretion may reflect intracellular lysosomal drug localization.


Assuntos
Fígado/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , Perexilina/farmacologia , Acetilglucosaminidase/metabolismo , Animais , Bile/efeitos dos fármacos , Bile/enzimologia , Relação Dose-Resposta a Droga , Feminino , Glucuronidase/metabolismo , Técnicas In Vitro , Fígado/enzimologia , Lisossomos/enzimologia , Lisossomos/patologia , Taxa de Depuração Metabólica , Modelos Biológicos , Perexilina/farmacocinética , Ratos , Ratos Endogâmicos
14.
Gut ; 29(12): 1715-20, 1988 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3220312

RESUMO

The effect of intermittent dosage with omeprazole on basal and pentagastrin stimulated gastric acid secretion and fasting plasma gastrin was assessed in eight duodenal ulcer subjects who were in remission. Omeprazole (20 mg daily) was given for a three day 'weekend' each week for two months. Twenty four hours after the first and eighth weekend, basal and peak acid output were still markedly suppressed (greater than 50%) compared with pretreatment. After the treatment free four days, however (just before the eighth weekend), peak acid output had returned to pretreatment values; basal acid output was still somewhat reduced (mean 3.6 mmol/l) but the difference from baseline was not statistically significant. Fasting plasma gastrin concentration increased slightly but significantly, from a baseline median of 17 pmol/l to 25 and 31 pmol/l respectively, 24 hours after the first and eighth weekends. All but two values (of 16) remained within the reference range. Before the fourth and eighth weekends, and again at 12 days and three months after treatment, gastrin values were not significantly different from baseline. Thus a 'weekend therapy' regimen with this long acting antisecretory compound produces substantial acid suppression, but for only part of the week, with modest and reversible changes in fasting plasma gastrin. It should therefore be suitable for efficacy testing for prevention of recurrence of peptic ulcer or reflux oesophagitis.


Assuntos
Úlcera Duodenal/metabolismo , Ácido Gástrico/metabolismo , Gastrinas/sangue , Omeprazol/administração & dosagem , Adulto , Esquema de Medicação , Úlcera Duodenal/prevenção & controle , Jejum , Humanos , Masculino , Pessoa de Meia-Idade , Omeprazol/uso terapêutico
15.
Gastroenterology ; 95(4): 1088-98, 1988 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3137115

RESUMO

Hepatocyte lysosomes disassemble materials derived from intracellular sources, including lipid-containing membranes, by a process called autophagy. In addition, hepatocyte lysosomes can release their contents into bile by exocytosis. Therefore, using both in vivo and in vitro models, we tested the hypothesis that acute pharmacologic induction of autophagy would modify the biliary excretion of lysosomal protein and of lipids. We treated rats with a single dose of chloroquine (10 mg/kg), glucagon (1 mg/kg), or control solutions and collected bile via bile fistulas. Both chloroquine and glucagon immediately caused a marked and parallel decrease in biliary excretion of three lysosomal enzymes, N-acetyl-beta-glucosaminidase, beta-glucuronidase, and beta-galactosidase, to 25%-30% of baseline values (p less than 0.01). This decrease was sustained for 2 h after glucagon and 4 h after chloroquine administration. In contrast, biliary lipid changes were minor: a slight lowering of biliary cholesterol secretion after chloroquine (p less than 0.05), but no change in biliary bile acids, cholesterol, and phospholipid secretion after glucagon. Changes in biliary excretion of lysosomal enzymes accompanying chloroquine and glucagon administration were associated with morphologic evidence of autophagy as assessed by electron microscopy and by increased fragility of hepatic lysosomes as assessed by latency of N-acetyl-beta-glucosaminidase. These in vivo changes in biliary lysosomal enzyme excretion induced by chloroquine and glucagon were confirmed in vitro using the isolated perfused rat liver. Thus, acute induction of autophagy results in conservation of hepatic lysosomal protein and has virtually no effect on biliary lipid excretion.


Assuntos
Acetilglucosaminidase/metabolismo , Bile/metabolismo , Galactosidases/metabolismo , Glucuronidase/metabolismo , Hexosaminidases/metabolismo , Fígado/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , beta-Galactosidase/metabolismo , Animais , Ácidos e Sais Biliares/metabolismo , Cloroquina/farmacologia , Colesterol/metabolismo , Glucagon/farmacologia , Insulina/farmacologia , Fígado/enzimologia , Fígado/ultraestrutura , Lisossomos/enzimologia , Lisossomos/ultraestrutura , Masculino , Ratos , Ratos Endogâmicos
16.
Regul Pept ; 20(4): 311-22, 1988 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-3368582

RESUMO

Vasoactive intestinal polypeptide (VIP) is released into the portal circulation by a meal stimulus, but is rapidly cleared from plasma. Although it is known to bind to receptors on liver cells, the role of the liver in the clearance of VIP is not clearly defined. We therefore studied the disappearance of VIP in recirculating and in single pass isolated perfused rat liver (IPRL) preparations. Disappearance of added VIP was rapid in recirculating IPRL experiments with a half life of ca. 30 min. In single-pass steady-state studies in which livers were perfused at 16 ml/min for 30 min, clearance of VIP was complete (16 ml/min) at concentrations of 500 fmol/ml, but clearance fell to 3 and 1 ml/min at perfusate concentrations of 8 and 40 pmol/ml respectively. Further experiments to evaluate whether VIP was disappearing in perfusate itself demonstrated substantial metabolism of VIP in perfusate which had previously been circulated through a liver for 90 min. The products of metabolism were identical to those found in the IPRL. We conclude that VIP is rapidly cleared as it passes through the isolated perfused rat liver model with a significant proportion of clearance attributable to release of a peptidase from the liver into the perfusate.


Assuntos
Fígado/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Feminino , Técnicas In Vitro , Taxa de Depuração Metabólica , Perfusão , Ratos , Ratos Endogâmicos
17.
Exp Pathol ; 33(3): 173-7, 1988.
Artigo em Inglês | MEDLINE | ID: mdl-3224678

RESUMO

During injury to the gastric mucosa, lysosomes become more fragile and lysosomal enzymes, which are activated at acid pH, leak into the surrounding environment. It is not clear whether these changes contribute to the mechanism of damage or are merely a secondary result of it. To test whether lysosomes modulate gastric mucosal damage, we pretreated rats with a lysosomal labilizing agent, Triton WR 1339 (1.5 g/kg) and histologically assessed mucosal damage in vivo after challenge with 30% ethanol. No significant differences were found in the length or depth of eroded mucosa: mean erosion length, Triton 23.9 +/- 6.6% vs. control 19.7 +/- 5.2%; mean depth (micron), Triton 19 +/- 4 vs. control 20 +/- 7. After a similar pretreatment regimen, rat antral mucosa was cultured, challenged with ethanol and damage assessed by release into media of previously incorporated mucosal 51chromium. With 15% ethanol challenge, no change in 51chromium release was seen: after Triton, 9.8 +/- 1.4% vs. control 10.3 +/- 1.0%. Triton pretreatment perturbed gastric lysosomes as shown in organ culture by significantly raised tissue lysosomal enzyme activities and increased lysosomal enzyme release into culture media after ethanol challenge. The lack of effect of this pretreatment regimen suggests that lysosomes do not have a major pathogenetic role in ethanol-induced gastric damage.


Assuntos
Etanol/toxicidade , Mucosa Gástrica/patologia , Animais , Radioisótopos de Cromo , Detergentes/farmacologia , Mucosa Gástrica/efeitos dos fármacos , Mucosa Gástrica/enzimologia , L-Lactato Desidrogenase/metabolismo , Lisossomos/enzimologia , Lisossomos/ultraestrutura , Masculino , Técnicas de Cultura de Órgãos , Polietilenoglicóis/farmacologia , Ratos , Ratos Endogâmicos
18.
Clin Exp Pharmacol Physiol ; 14(10): 791-5, 1987 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3442950

RESUMO

1. Neurotensin is released from the intestine into the portal circulation and to exert a systemic effect it must traverse the liver intact. 2. The role of the liver in neurotensin clearance was examined using the isolated perfused rat liver preparation. Two concentrations of neurotensin were used to determine the extraction capacity of the liver. 3. Approximately 10% of the added neurotensin (with either dose) was extracted in a single pass through the liver. This extraction rate was low when compared to previous studies with cholecystokinin (60% extraction in a single pass) and vasoactive intestinal peptide (100%). 4. It is concluded that there is a small but high capacity for direct extraction of neurotensin. This low direct extraction percentage supports our previous contention that the major influence of the liver on the metabolism of neurotensin is by the release of neurotensin degrading peptidases into the circulation.


Assuntos
Fígado/metabolismo , Neurotensina/metabolismo , Animais , Feminino , Técnicas In Vitro , Perfusão , Radioimunoensaio , Ratos , Ratos Endogâmicos
19.
Endocrinology ; 120(4): 1397-402, 1987 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-3549259

RESUMO

Neurotensin is released from the intestinal mucosa into the portal circulation and, to exert a systemic effect, it must traverse the liver intact. We examined the potential role of the liver in neurotensin clearance using the isolated perfused rat liver model. With N-terminal and C-terminal directed RIAs and HPLC, we demonstrated rapid metabolism of intact neurotensin to inactive N-terminal fragments in the isolated rat liver system. The disappearance half-lives of C-terminal and N-terminal immunoreactivity were 20.4 +/- 6.0 min and 82.7 +/- 7.7 min, respectively, (P less than 0.002). To assess whether this neurotensin disappearance might be due to metabolism within the perfusate itself by a peptidase released from liver, we further incubated neurotensin in perfusate previously circulated through liver. A rapid and progressive breakdown of intact neurotensin to N-terminal fragments was again shown. These data demonstrate that a substantial proportion of the hepatic clearance of neurotensin is attributable to release of a peptidase by the liver into the circulation.


Assuntos
Fígado/metabolismo , Neurotensina/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Feminino , Meia-Vida , Técnicas In Vitro , Fragmentos de Peptídeos/metabolismo , Peptídeo Hidrolases/metabolismo , Perfusão , Radioimunoensaio , Ratos , Ratos Endogâmicos
20.
Clin Exp Pharmacol Physiol ; 13(10): 745-50, 1986 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3802579

RESUMO

The effects of ethanol on hepatic lysosomes are poorly documented. This study examined the biliary release of lysosomal enzymes, a marker of the hepatocyte-to-bile excretory pathway, after ethanol administration in the isolated perfused rat liver model. At concentrations similar to those reached in human plasma during social drinking, ethanol markedly decreased biliary lysosomal enzyme output and bile flow in the rat. Ethanol did not affect hepatic activities or the release into perfusate of lysosomal and other subcellular marker enzymes. Hence, ethanol may potentially inhibit hepatocyte-to-bile excretion of other compounds processed through lysosomes.


Assuntos
Acetilglucosaminidase/metabolismo , Bile/enzimologia , Etanol/farmacologia , Glucuronidase/metabolismo , Hexosaminidases/metabolismo , Fígado/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , Animais , Feminino , Técnicas In Vitro , L-Lactato Desidrogenase/metabolismo , Fígado/enzimologia , Lisossomos/enzimologia , Perfusão , Ratos , Ratos Endogâmicos
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